As discussed in co-owned U.S. patent application Ser. No. 12/116,195 entitled “Algorithmically Generated Topic Pages” and co-owned U.S. patent application Ser. No. 12/116,198 entitled “Micro-Bucket Testing for Page Optimization”, now U.S. Pat. No. 8,126,930, all of which are hereby incorporated by reference, presentations in browsers can be composed of modules with rich media such as images, video, and audio. An example of such a module is a Wikipedia article on a particular topic, which might be presented in a web page related to that topic by a provider or website such as Yahoo! or Google in a browser. Another example is a rich multimedia advertisement.
Presenting such media to a browser entails significant latencies, even over a broadband connection. Moreover providers, such as Yahoo! and Google, have service level agreements (SLAs) that include requirements involving such latencies. For example, a service level agreement might require that a specific web page be displayed “within 800 milliseconds, 99.85% of the time.”
Web caches significantly help in reducing these latencies. However, cache misses are inevitable in a world where web pages are added and changed almost continuously. If cache misses are frequent enough, SLA requirements might not be met and revenue might be lost.